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Tracking patients’ changes in fractional flow reserve (FFR) from before to after a percutaneous coronary intervention (PCI) may provide useful information, according to new research published in JAMA Cardiology. Individuals with the greatest change in FFR were less likely to experience vessel-related events and demonstrated greater symptomatic relief.

“The potential of any post-PCI FFR value to prognosticate an outcome remains low,” lead author Stephane Fournier, MD, and co-authors wrote. “While a final hemodynamic result can be identical, the improvement in FFR value can be different and might have a different meaning for the patient.”

To investigate this theory, Fournier et al. performed a post-hoc analysis of the FAME 1 and FAME 2 trials, which evaluated the efficacy of FFR-guided PCI. Their work included 639 patients with 837 lesions which had FFR values measured both before and after PCI.

Vessels were classified into three groups based on the change in FFR: below 0.18, between 0.19 and 0.31 and above 0.31. Compared to individuals with vessels in the highest tertile of change, those in the lowest group were twice as likely to experience a vessel-oriented clinical event—including cardiac death, revascularization or myocardial infarction—over two years of follow-up.

A total of 9.1 percent of patients with FFR values budging the least had one of these events, compared to 4.7 percent of patients with FFR values changing by more than 0.31. Fournier and colleagues pointed out the change in FFR was a stronger predictor of these vessel-related events than either the pre- or post-PCI FFR value alone. Symptomatic relief assessed by Canadian Cardiovascular Society angina class was also significantly greater with higher changes in FFR.

“This study confirms and quantifies our clinical intuition, namely, that the larger the ΔFFR, the larger the symptomatic improvement,” the authors wrote. “These data extend the findings of the Objective Randomised Blinded Investigation With Optimal Medical Therapy of Angioplasty in Stable Angina (ORBITA) trial, which showed a physiology-stratified effect of PCI on symptomatic relief, to a broader patient population.”

The potential mechanisms for these findings are still “largely speculative and multifactorial,” according to the authors. However, they cited diffuse coronary atherosclerosis and suboptimal stent deployment as possibilities to explain lower post-procedural FFR—and thus, smaller changes in values. On the other hand, low pre-PCI FFR values could contribute to above-average relative changes after PCI because there is more room for improvement.

“Measuring FFR before and after PCI provides clinically useful information, because a low ΔFFR appears to be a surrogate marker for a higher risk population,” Fournier and co-authors wrote. “These data might, in the future, be derived from coronary angiography when the procedure has been carried out with a regular guide wire,” as was demonstrated in the FAST-FFR study.